The Great Lakes - Part Three

An alternate track is via the Illinois River (from Chicago), to the Mississippi, up the Ohio, and then through the Tennessee-Tombigbee Waterway (combination of a series of rivers and lakes and canals), to Mobile Bay and the Gulf. Commercial tug-and-barge traffic on these waterways is heavy. Pleasure boats can also enter or exit the Great Lakes by way of the Erie Canal and Hudson River in New York. The Erie Canal connects to the Great Lakes at the east end of Lake Erie (at Buffalo, New York) and at the south side of Lake Ontario (at Oswego, New York). Statistics: The Great Lakes contain 21% of the world’s fresh surface water: 5,472 cubic miles (22,810 km3), or 6.0×1015 U.S. gallons (2.3×1016 liters). This is enough water to cover the 48 contiguous U.S. states to a uniform depth of 9.5 feet (2.9 m). Although the lakes contain a large percentage of the world's fresh water, the Great Lakes supply only a small portion of U.S. drinking water on a national basis (roughly 4.2%). Winter 2009–10 somewhat mild, the precipitation was below normal for the Great Lakes Basin. Mean lake levels are thought to be slightly below or at their levels of 2009. An ice jam in February 2010 dropped the level in Lake St. Clair. Since the jam was removed the level has come back to its average. As of March 2010, the lakes were at the level, or slightly below, where they were in March 2009. The combined surface area of the lakes is approximately 94,250 square miles (244,100 km2)—nearly the same size as the United Kingdom, and larger than the U.S. states of New York, New Jersey, Connecticut, Rhode Island, Massachusetts, Vermont, and New Hampshire combined. The Great Lakes coast measures approximately 10,500 miles (16,900 km); however, the length of a coastline is impossible to measure exactly and is not well-defined measure (see Coastline paradox).